There are two major categories of heavy duty hand cleansers (HDHC) currently on the market. The first include formulations without solvent and with or without scrubbing micro-particles, typically derived from vegetable, mineral or organic origins. These products contain some surfactants which act by emulsifying greasy stains. These scrubbing micro-particles provide a mechanical effect during the hand washing and, thus, increase the cleansing power of the preparation.
The second category of so called heavy duty cleansers include formulations with solvents present, with or without scrubbing particles, with surfactants (soap and/or synthetic and/or semi-synthetic surfactants). These cleansers containing solvents combine the emulsifying properties of the surfactants with the solubilizing properties of the solvent The presence of micro-particles will increase the cleansing power of these formulations as in the case of non-solvented formulations. The solvents are generally hydrocarbon solvents without any aromatics (or trace amounts present only) and used at an average concentration of 10 to 30%. Terpenes such as d-limonene are also often used at a concentration of 1 to 10%. Hydrophilic solvents such as propylenic glycol ethers are rarely used. Solvents are often criticized for their defatting properties on skin which may induce irritation.
D-limonene has an aesthetic advantage of having a very pleasant orange aroma while functionally it is very effective on grease, but a drawback to this solvent is the fact that, in its pure form, it is flammable and is considered harmful to the environment. In addition, some allergies to oxidized terpenes are described in scientific literature. This is why d-limonene for example is systematically protected from oxidation using a cosmetic anti-oxidant (in most cases the anti-oxidants used are Butyl-Hydroxy-Anisol (BHA) and/or Butyl-Hydroxy-Toluene (BHT) which also have a sensitizing potential). Hydrocarbon and terpene-based solvents have a low biodegradability potential and are known for having a significant ecotoxicity on aquatic life.
The use of surfactants only to obtain a high level of cleansing efficiency is possible but needs a high concentration of active matter which is costly and not suitable in terms of the environment. It would be very advantageous to provide a cleanser having a combination of solvent, surfactant(s) and scrubbing microparticles would allow one to reduce the total quantity of active matter in the finished product.